As part of monitoring patients' health, medical professionals evaluate patients' cardiovascular systems through cardiac physical exams. One of the tests that is useful to medical professionals in evaluating a patient's cardiovascular system is an abdominojugular reflux (AJR) test, which is used as a marker for indicating cardiac dysfunction.
In accordance with conventional AJR-testing techniques, a medical professional applies slow, steady pressure to an abdominal region of a patient while observing the patient's neck for a minimum period of 10 seconds. During that time, the medical professional observes the patient's neck to monitor changes in their jugular venous pressure by watching for changes in the person's jugular venous pulse (JVP). In healthy patients, the JVP rises less than 3 centimeters from an initial location and then falls down even while pressure is maintained. This is considered a “normal” response, and results in a negative AJR test—one indication of good cardiovascular health. If the observed JVP remains above 3 centimeters during the 10 seconds of sustained pressure and drops abruptly by more than 4 centimeters upon release of the pressure, however, the result of the AJR test is positive. A positive AJR test is a highly specific indicator of potential problems with the patient's heart, namely, it indicates that a right side of the patient's heart is unable to accommodate an increase in venous return.
Conventional techniques for performing AJR tests are inconsistent due to variations in the skill level and techniques across medical professionals, however. Such techniques are inconsistent because they rely on tracking changes in the difficult to observe JVP. The JVP is a faint and difficult to discern signal that requires a significant degree of training to reliably identify. As such, AJR tests are performed almost solely by skilled physicians, making their use outside a clinic or hospital environment cost prohibitive. The drawbacks of conventional AJR-testing techniques render them less than ideal in many cases.